A study of the internal anatomy of Acanthocephala thomasi Uhler (, )

Item Type text; Thesis-Reproduction (electronic)

Authors O'Connell, Cornelius Varley, 1935-

Publisher The University of Arizona.

Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.

Download date 29/09/2021 18:01:14

Link to Item http://hdl.handle.net/10150/551407 : r' ’i- ■

. . A STUDY 'OF THE INTERNAL ANATOMY OF : • ACANTHOCEPHALA THOMAS I UHLER . (Heraiptera, Coreidae) ry: V '

'; ' ' ' L. : Z::,; \

:Coriieliuis V arley■ ;0 ‘C o n n e ll,■Jr.

vc 1 A Thesis Submitted to the Faculty of the

v :'i DC p ARTMENT;OF ENT OMOLCGY :■

. ,

' v : / Iii Pa.rtial Fulfillm ent of the .B.equirements

; - For the Degree of , ,

,e ^; , MASTER OF.SCIENCEy ' \ ' :

' , In the Graduate College

;y ’ : ■ 'UNIVERSiT Y ^ F ARIZONA .. ^ y ; : :;n ‘ :v •

J'vl

■ I- : v.o./. ■.: v. ■ ■ 1 w -

h !■• * !■• :=- 5. L •» J ' .. .. ^ ■ j 1 ' , j. if/' : j—... ■\ ■

» - , f - 1 W ' X v , " V-

. ' : ' ; j, . .1 / J'/i'-'- ' ' '

-

% - -x" : -:.i :■ 1 - i -

' • " ■ '.. ■ . - _'r

••• ■- . ' . ' -■ '' ‘‘ - . ; / >:-a < W ? / '

5 5

STATEMENT BY AUTHOR

This thesis has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library,

Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of ' source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in their judgment the proposed use of the material is in the interests of scholars hip. In all other instances, however, permission must be obtained from the author.

SIGNED: -■'V - . ' .; - /

APPROVAL BY THESIS DIRECTOR

This thesis has been approved on the date shown, below:

W illiam L„ . Nutting Associate Professor of Entomolo^

ii ACKNOWLEDGMENTS

I am indebted to Div William.',L» Nutting (University of Arizona) under whose guidance the investigation was carried out« Without his direction in.laboratory procedures, illustrations of the Systems and preparation of the thesis itself, the Study would not have been possible.

The author would also like to acknowledge the aid of the follow­ ing people during the course of this study: Miss Marian Adachi and

Mrs. Lois Koenig (University of Arizona) for supplying material used in the investigation, and also for Miss Adachi!s assistance, in the pre­ paration of the drawings| and Mr. Peter Ashlock (United States National

Museum) for the identification of Specimens.

ii i :

t a b i j e o f d W iE m T s -/ ■, ' y'. , . ; \ A-' P age,

, List of Figures,,« . . .> , o‘ o e> o e 9 o *eVo o » o »

Abbreviations used in Figures. „ ,i» o « » . ° ° ,':':vi

•' INTRODUCTION AND LITERATURE REVIEW...... ' " T '

i,MATERIALS AND' METHODS, i ..^A i ' . ’. • . ,

' THE M ALE REPRODUCTIVE SYSTEM ...... Y;>;5 '

General, structure of the abdomen. . ... e © e -o o O', c o o e > P, o

0, 0 ov® ® o. > ®- P O O p e« o«; o,-o o © e p ©, © p e o , © o ' 5 V ' ' . o a a O e p,p ® op o o o,o e • o a * o p o o 6 f. - ■ , . .. .::v THE F E M A L E ' REPROD UC TIVE SYSTEM...... ' 9 ■

General structure of the abdom en».o'* ® ©® o...... o o e o p ©o ®o ®o *o ®o p© o o e ,• 9 , Ovtslti v a r ie 0 s and dued u cts t s ©o p ® », @ © © »© © © © © © ® ® » ® © © © ,© © © © © © © ©, © © © • 9 . . / ; •. , . -a,;' , ■ ' .. . ■ » CD.Vip O S it O r © ©,: © © ® ©■ © © © © © © © © © ©,©.©*©.©© © © © © © o ©op © •*© e » a, ©. © © © © ©, io ;

w a-;- • . , . ■ ; ^ : T H F : NEE V O U S SYSTEM... ».© © o © o © .© ® ©' e.o © © © © © © © © © p ©._©,. 12 :

■ : THE AFIMPSTAB-Y CANAL..>,. . ...iivu, 15 'A;;: ■ . ; ■ S a liv a ry ■,glaho-S...... ,.,.,. *..»,«•••«.». «•. v . *...... ,T r -'v

' " . THE CIRCULATORY SYSTEM...... 18 ■ - y : ■

' .... DISCUSSION AND OONCLHSIQNS.. .i,...... Y. .-.... 20

,S XJIvi jAjH.'Y" © ©oe © © © © e » © o p o * © © ©o© e '© ©' ©;, .»*’© © , «, © p e e o © o © © © 22

•v;';; ;;L.li?ERATUR CITED. .■:. . . o © '© '© © o. ©- .© '©' © © © © © - :'::23

: , :\.V

V * ' a '; LIST OF FIGURES

F igu re , x " . '. , . . P age

1, , " Male reproductive system , dorsal view (x 8)o„ „ „ „ „ « » „

2« Phallus of male reproductive system, anterior

Vi Q'S/P" (x 0 ^) O 0 o !o e e « , o a a « o o « a » e • « e o o e ® » o .* » • o e o o p o; o e e » 25

3. Aedeagus and endophallus, anterior view (x 2Q)„ „ „. „ 25

4. Left side of brain and su b oes ophageal ganglion (xSd). . 25

.51: : 'a’Eemale. r ep roductive1. s ystem , dor s al view (x 8)4. . . «'

6. Posterior region of female abdomen,■ ventral •

V iew (x U s) 6 o o o e © o

7, First valvula of female ovipositor, dor sal - view (x 28.) 26 V

8© Second yalvifer and .valvula of ovippsitor, •dorsal '

• ' ■ V iew (x '38) a, © « » © * * .© a ©%© e". o © © © © e, ©: © a © © © ©- e « » © a .© a © © © © © © ::26;;;4

9© Brain and ventral nerve cord, dorsal view (x 8)4© © „ © 27

10. :Alimentary canal, dorsal view (x © © ©. . a ,e e e o « » o. e 28 .

11© Left salivary gland and accessory structures, ven tra l viev: (x L © © © © © © « «■© ©■© ©, ©«©.©«© .© © © © •© ©« © © © © © 28

Dorsal blood vessel, ventral view (x 11)© © .©•©.© 29

. ■ .v T ABBREVIATIONS USED IN FIGURES

AcGl accessory gland • ' Ost ostia , . , Aed aedeagu's • Ov ovary - : . An - anus' ' ■ - vV: : . Phy pharynx _ ' ■ ' • y y AM • abdominal nerve Pmr paramere AntNv antennal nerye Ptn Gng prothoracic ganglion Aid ao rta : ^:.i' Py pylorus . bcpx:; , bursa copula.trix . RGIR repugnatorial gland reservoir 1 Br v ' protoic erebrum ^' Rect rectum Goe Con circumoesophageal . SID salivary duct SlGl . salivary gland De ductus ejaculatorius . Soe Gng suboesophageal ganglion dt- alary muscle " : Spt spe rmatheca. Due ' - ,' : 'iductifer u : - y'; Spt G1 spermathecal gland EnpR endophailus • Stp stapes ’ .- • ■ Gca gdstrie caeca ■ T A te r gal arm . . Gen Gap genital cnpSule . Tes - ' testis GN . genital nerve . •’ Vd yas deferens V Ht y . h eart 1 Vent first portion of mid-gut LMs lateral mesothoracic 2 Vent second portion of mid-gut - ; v'A : n erv e . : , 3 Vent third portion of mid- gut LMt lateral metathpracic 4 Vent fourth portion of mid-gut ■ nerye: ■ YY'/ ^ ■■■■■' VI valvula DPN ; . ■ lateral prothoracic ■ : Vlf valvifer y . . y. : nerve ^ _ . Vsm vesicula seminalis MaT malpighian tubule : Ode oyiductus communis Qdl y; aviductus lateralis Oe • oesophagus OP del • oc ellar pedicel • INTRODUCTION AND LITERAT URE REVIEW

. This study was undertaken in the hope that it .might, in some

small way, increase our knowledge of the internal anatomy of the hemip­

terous . Some of the families of this order have been studied

quite extensively insofar as reproductive and digestive systems are con­

cerned, The families Miridae and Cimicidae are good examples of this,

. Other groupsy on the contrary, have been the Subject of little investiga-

, tion as is the case in the family COreidae, Wooley (1949) made a study

of the digestive, reproductive, and nervous systems in the box elder

bug, Leptocoris triyittatus (Say) (Coreidae), In 1951, he studied the

circulatory system of this same , and in these two works he has

given a fairly detailed description,of these system s. He fails to mention

anything of the so-called sympathetic: nervous system , however.

An excellent work on the nervous system of the large milkweed

bug, Oncopeltus fasciatus (Dallas), by Rutschky and Stryjak (1955) proved

useful. The neryous system in this member of the family Dygaeidae was

found to be very Similar to that in the coreid under study,

A comprehensive study of the alimentary canal of the order Hem-

iptera was made by Elson (1937). The members of the order were 2

Studied in ligM of their different feeding habits: plant suckings preda-

ceous, algae-feeding^ fungi-feedingg and the blood«sucking insects^. The

treatment includes general but valuable information for anyone interested

in this sy&teiru ;: i * - - , _ \ , ,

Several outstanding works on insect genitalia have been done in

the past» The reproductive system of the large milkweed bug, One op el- tus faselatus (Dallas); was-described in great detail by Bonhag and Wick

(1953)» Both the male and female systems were treated in this excellent worko As was the case with the nervous system, the similarity between

the reproductive system of this lygaeid and Acanthoc ephala is Striking.

A number of classic works on insect genitalia include those of: Newell ,

(1918), Cramp ton (1922), Singh-Pruthi (1925), Snodgrass (1933, 1936,

1957), and Michener (1944)o; MATERIALS AND METHODS

Specimens used in this study were collected on velvet ash trees,

Fraxinus velutina Torr. , on the Santa Rita Range Reserve 40 m iles south of Tucson, Arizona. Some of the specimens were immediately frozen; the rest were maintained alive in gallon jars with cheesecloth stretched across the top. Vials with cotton plugs provided a source of water. Several different foods were tried over a period of five months.

Small mesquite shoots were Supplied frequently until they became too dry in late October. The diet was then changed to green beans and

Summer squash. Finally, only green beans were given to the insects.

No attempt was made to correlate type of diet.with rate of survival, although Some specimens were alive after five months under these con­ ditions. Several were dissected shortly after they had died; often the insects were almost completely desiccated internally with only a trace of the abdominal portion of the alimentary canal recognizable. It was not determined whether the deaths were due to a dietary deficiency, to some abnormality in the rearing conditions, or simply to senility.

From time to time a few of the living insects were preserved in SO per cent alcohol. Later, these were compared with the specimens 4 that had been frozen, and the latter seemed to have been much better preserved for internal morphological studies. For the most part, the dissections were made on preserved insects under a stereoscopic dis­

secting mic r os cope, the specimens being pinned out in a wax-bottomed petri dish under 80 per cent alcohol. Certain structures were removed to a watch glass and placed under alcohol for more detailed study.

Instruments for dissection included No. 3 and No. 5 Dumont watchmaker's forceps and Small scissors for separating sclerotized areas. A method for inflating the phallus described by Ashlock (1957) using solutions of alternating osmotic pressures, proved unsuccessful on this insect.

Drawings were made to scale with the use of an. ocular grid and squared paper. THE MALE REPRODUCTIVE SYSTEM

■ .'v' General structure ofthe abdomen (Figure l).- Dor sally, there .

are seven distinct ahdqrnimal segments preceding the bulbous genital

capsMe in the toale« The eighth abdominal segment is a simple chit

inous ring, retracted into the seventh Segment when the genitalia are

not in Use. The genital capsule is the modified ninth abdominal seg- ;

ment hohsing the phalluS: the alimentary tract or

proctiger. The capsule is open dorsally and the parameres and proc-

. tiger may be seen lying within the cavity of the capsule. Vent rally

ehly. six abdominal segments are clearly visible anterior to the capsule,

" the first sternite having fused with that pf the second. , ; y G

Testes and duets (Figure l)» The paired testes are attached to

the .pleural areas of the fourth abdominal segment by branches from the

third abdominal spiracular tracheae. Each testis is dull white tinged

with reddish-orange and is composed of seven testicular tubules enclosed

in a membranous Sheath, Leading posteriorly frem. each testis is a

simple tube of fairly uniform diameter, the vas deferens, which widens

posteriorly into a seminal yesicle. Immediately behind this point the ■

two yasa deferehtia joinl and on the: anterior margin of this junction ;; ; there is a series of outpocketings' representing the accessory glands„

The tube continuing posteriorly from the junction of the vasa deferentia

is the ejaculatory duct. It is milky white and of uniform diameter^ until

it widens into the balloon-like erection fluid pump. Within the lumen-of

the ejacuiator-y duct lies a ■structure resembling a bottle brush, A canal

runs through the center of this brush, and this, is the true sperm tube.

Bonhag Shd Wick State that nothing IS known concerning the source of the

erection fluid in Oncopeltus, and speculate that it might be produced by

the epitheliurn of the erection fluid reservoir. This fluid passes , from ;•/ : , . : . . ■ ,V h: : . : ■ ''d;: ;:a the reservoir through the ejaculatory duct and into the phallus. The

mechahism of the erection proCe:Ss in Onebpeltus is described-by Bonhag

and Wick (1953)./ Although these vrorkers described an erection fluid t .■ . : : . > : i V'-"-:'-' ■.• - a - ■ -. ■. - - -v v A ■ . reservoirvin Oncopeltus, a comparable structure could not be found in •

Acanthocephala. A A , • ' yA-'/. /

■ External genitalia (Figures 2, 3). The phallus is composed of

two parts, the' phallobase and. the aedeagus. There is not the typical

phallohase and retractible aedeagus-ehdophallus assdciation commonly

described for hemipterous insects. The phallohase typically has a

retractible aedeagus attached. to its distal end, and within the aedeagus,

lies the endophallus. which is extrasible. In this insect the aedeagus is

permanently attached to the phallohase and cannot be extruded, while

the endbptiaTLus can be forced out of the aedeagus during copulation. ' ; •'

However3 within the phallohase there is a complex structure housing

: part of the end/ophalius, ,w^ Will be . described below. ' .;

;:'V "" The phallus is connected to a structhr'e which is a modification ;

of the wall of the genital capsule. This: structure is sim ilar to. the

Pvmcchanism described in Qncopeltus by Bonhag and Wick (1953), The .

stapes is a yoke ^ sclerotiWed area' -at the ante ribr mar g of the f

phallobase,- when the latter is retracted.. The dors bilateral areas of

the stapes^> ftiCulate yvith two chltinous bahds, phallic arms s which are ‘

a extensions of the posterior margin of the genital capsule. These artic­

ulations are cove fed by ashield-like plate, the promotor apod erne. A :

:membrappus':Scptnna sepaf ate® the phallobase from the abdominal cavity.

and in the center of this septum is a sclerotized area known as the v." V ::

ductifer. The sperm tube within the ejaculatory duct passes through an

orifice on'the,upper margin of the stapes and becomes the sinuous,

;chiiinohs: endpphalhis jiis t p oste rid i to the Sthp e.S.

The erection fluid is admitted to the phallobase through two . ■

dppenln'gs dif entrance, of the sperm duct. Posterior to-d

the stapes is a pair of Sclerotized piates, one of which gives ris e to the ,

shield of the ‘endophalluS. The other, lies as a small plate ppposite the

' Origin of the aedea.gus. The endophallus originates on the posterior

. face of the. stapes and form's two lodps before passing into the cork-. ..■ * / screw-like' aedeagus. , Another pair of sclerotized plates form the distal

‘;V> S

./d -y-'t r/.h, V-

part of the ph.allobase3 the remainder of the external area of the latter

being membranous „ The parameres (gonostyli of Bonhag and Wick (1953) )

lie well within the cavity of the genital capsule and are connected to the:,

membfaneliningthecapsule. ,■ \

< .

■. ' ■■ ■■ . : ■ " ' ■ ■■■;' - ; v

' .'V,", THE FEMALE REPRODUCTIVE SYSTEM

. - '. .1 ■ i _ , ' ■ , , ' , ■ ■ • j General structure of the female abdomen (Figure 4)» Nine seg­ ments are visible on the dorsal surface of the female abdomen; vent rally six segments are easily distinguished® The first apparent abdominal

Sternite is actually composed of sternites one and two® Sternite seven, bears a Transverse slit immediately fplldwed by two large triangular lobeSo Segments eight and nine are each represented by a dorsal plate and a pair of paratergites which lie adjacent to the triangular lobes of segment seven* The venter of the eighth segment is represented by a membranous area between the bases of the first valvifers* The ninth venter has invagihated to form the genital chambere The proctiger, composed of segments ten and eleven* lies within the genital capsule<>

Ovaries and ducts (Figure 4), The paired ovaries are connected to: the splracular tracheae of segment three® These tracheae give off a number of branches which envelope and lend some support to the- gonads»

Each milk-white ovary is composed of seven ovarioleSo Apically each ovariole narrows, into a terminal filament which together form the sus­ pensory ligamenta This is attached anteriorly to the heavily sclerotiaed cervical ring. From each ovary a simple lateral oviduct passes caudad

. ■ V 9 ' V--, ■ ■ V 1 : ■ . 10 •

. to a point in the sixth abdominal segment, where the two fuse. From this point the common oviduct take s the form of a. bursa copul at rix„ On ,, the dorsal surface of this bursa are found the spermatheca and the • paired acces sory glands . The former is a sausage-shaped’ or ga.n with : a purplish colored capsule connected to its base. In all specimens examined, this capsule was found associated with the spermatheca, and it is possible that the structure serves as a spe rmathe cal gland. Histo­ logical evidence is needed to: confirm this point. The duct from the

Spermatheca opens .through the dorsal surface of the bursa. The paired accessory glahds are Simple tubes of a'milky color, so that they are difficult to distinguish from the roof of the bursa. The ducts from these glands pass laterally, .then yentrally, to Open into the bursa at the base of the .Second yalviferS. . -

■ .Ovipositor (Figures 5, 6, 7). The large triangular yentral .lobes . of the seventh abdominal s egment are the first valvifers of the ovipositor

If these lobes are Sp read late rally the bur sa and the first valvulae may be seen between them. The first valyplae are joined to the first valvi- fers anteriorly by thin chitinous bands, The first valvulae are for the most part heavily sclerotized except for a small dorsal mernbranous area. The second valvulae lie above the first yalvulae, their rami being continuous with the second valvifers. The latter are continuous with an arm from the ninth ter gum» The second valvulae are heavily sclerotized except for their membranous apices, which are spinous and modified into hook-like processes* Third valvulae are not present* ■ ' . :■ ■■■■■ / / / ; ', . . ■■ ■■ .v ' ' '. \ ' / ■, ,' _ - ' , - - . ; v Snodgras s (1935) claim s that the third valvulae are abs ent als o in Anas a tristis but are usually found in other Hemiptera* / v- ' ■ THE NERVOUS SYSTEM

v, Unmsxial modifications of the characteristic inject nervous system are known to exist among seyeral different orders. This is especially true among some of the Hemiptera, Wooley (1949), for example, found a considerable amount of ganglionic fusion in the brain and ventral nerve cord of the box-elder bug, Eeptocoris trivittatus (Say) (Coreidae).

The presumed segmental lobes of the brain have undergone con­ siderable fusion in Acanthocephala (Figure 9), Protocerebrum and, to a less extent,deutocerebrum, are distinctive lobes of the brain which lie in the posterior portion of the head capsule. The t rito cere hr al lobes have fused completely with deutocerebrum and are no longer recognizable.

The lobes of the deutocerebrum, bearing one pair of antennal nerves, lie slightly anterior to the protoderebrum. Optic lobes originate on the ant e r o - do r S al surface of the forebrain. Paired ocellar pedicels arise from the dorsal surface of the protocerebrum. There is no evidence of a single median ocellus. The tritocerebral lobes are presumed to be at the origins of the circumoesophageal connectives. Two pairs of nerves originate on the suboesophageal ganglion; the anterior pair passes forward in the head to innervate the proboscis, the other leads posteriorly into the

12 13

cervical region. A single large connective passes from the posterior

margin of the suboesophageal ganglion to the prothoracic ganglion (Fig­

ure 9)» Two pairs of lateral nerves arise from this ganglion. The

anterior pair (LPIN^) innervate the prothbracic leg m uscles. The second

p a ir (•LPN2) pass caudad to the mesothoracic wing muscles

A large ganglion lying in the m eso- and metathorax terminates

the ventral ganglionic chain (Figure 9). This ganglion has been called

the central ganglion by Hamilton (1931) and the pterothoracic ganglion

by Malouf (1933). Altogether, eight pairs of nerves and a single median

nerve originate from this ganglion. The first pair of lateral mesothor-

acic nerves (TiMs ^) arise from the anterior margin and innervate the

mesothoracic leg muscles. The secondpair of lateral mesothoracic

nerves (HMs^) bifurcate once (a, b), one portion (a) dividing three more

times (c, d, e). Nerves a and b innervate mesothoracic leg muscles;

c, d, and e innervate mesothoracic wing muscles. The third pair of

nerves, the first pair of lateral metathoracic nerves (LMt^ ), lead to

the metathoracic wing muscles. The fourth pair. Second pair of lateral

metathoracic n e r v e s (LMt^)* bifurcate once (a, b) while branch a d iv id e s ■ " ' V , y e ' . v ... ' " ' - V '■■■ ' - ' ■ . ' . again (c). The metathoracic leg muscles receive a and b; the other (c)

innervates the reservoir of the metathoracic repugnatorial gland. Four

more pairs of nerves (AN^ originate nearer the midline and lead to

the abdominal viscera. A single median nerve (GN) runs posteriorly > - • -

, / 1 ■* • 14

from tills central ganglion. It bifurcates once in Segment.six (GN, :4T v / .4% then passes into segment seven and branches again (GN-^h, * The first

nerve (GNj) divides once (a, .b)j .branch a leads to the common oviduct^

while the other branch (b) innervates the ventrd-lateral region of the •v.: A

posterior abdomen. One nerve (GNg) divides into three branches, a, b,.

y’ and c. The accessory glands, bursa, ahd rectum are innervated.by ..

nerveS: a, arid bj the spermatheca receives the third (c). The other

nerve (GNg) divides twice (a, b, c), the first two brariches (a, b) inner-

vating the accessbry glands, bursa and rectum; the other (c) passing to :

the rectum alone, : ■ : • ' : '• , ' ' -^l::; '

It was not possible to work out the details of the so-called

sympathetic nervous system with the material, available. The corpora s . . . . c h ' ...... ' : . y : : cardiaca, corpora allata, and fro n tal ganglion were not found in their

expected positions, but this is not surprising in light of the extreme : . • ;

cephalization already noted. Additional material arid riistblogicai pro­

cedures may be necessary to complete this aspect of the nerVous system

■4 : ,

■ v; , ■ The digestive tract and as sociated structures, in Acanthocephala —:------greatly resemble this" system as. described in other coreids, particularly

The squashbug; Anas a tristis. (figure 10). According to Snodgrass (1935) the mesenfcer.on is the functional Stomach or ventriculus in insects.

Breakey (19.36), in his description of the digestive system of the squash

/ . . ' . . ' ' ; : v. " '' : V;:: ' "''l'':'-' i t bugs subdiyided the ventriculus into three regions following the work of

Weber (19 30), Els on (T937), - in ,his comparative study of the Hemiptera, recognized four .areas in the mid-gut or mid-intestine. Wooley (1949)1 in his study of the box elder bug, restricted the term ventriculus to the 1 : first region of the mid-intestiiie. In this work the terminology of Wo ole y haS been followed for the m ost part, particularly in regard to the number of subdivisions of the mid-inte stine. 1 ,'v . ;'/f '.

. This insect possesses typical sucking mouthparts, similar to those described for Leptocoris trivittatus by Wooley (1949). The pharynx lies anterior to the brain as a sclerotized tube with an grooveda dorsal •: surface. Dilator muscles are. inserted.on the dorsal ^surface of this tube providing a sucking pump mechanism for the intake of liquid foods. The pharynx passes through the tritocerehral region of the brain. aS a very

: ' . ii' - .Ai'''is m ain':; W v.-'.t small tube,, then into the prothorax as the narrow undifferentiated oesophaguSo ha the mesothorax, it widens slightly into the ventriculus or stomach proper. The ventriculus, which is sac-like and often greatly distended With liquid food, extends to the fourth abdominal segment, where it becomes differentiated into the second region of the mesenteron.

This portion now turns anteriorly to segment three as a narrow tube and then posteriorly again to abdominal segment five. Here, it loops anter­ iorly to join the larger, tube-like third region. This portion enlarges as it passes anteriorly to the second segment, then narrows appreciably, as it loops eaudad again to the sixth Segment. At this point the fourth region of tbe mid-intestine becomes differentiated. This portion of the mid-gut has received a.great deal of study by different workers. Gastric caeca are borne on this region as they are by many other hemipterous insects.

According to GlaSgow (1914) these caeca provide a safe place for the multiplication of the normal bacteria of the alimentary canal. The fourth area of the mid-gut runs transversely in Segment six Until it meets the pylorus. This region bears two diverticula, each giving rise to two malpighian tubules. These tubules are typical and coil extensively in the abdominal cavity. Posterior to the pylorus (ileum of Wooley (1949)) is the large rectal sac which then narrows into the rectum proper. The latter opens to the outside through the anus which is enveloped by a solerotixed, circular plate (proctiger) formed from the ninth and tenth abdominal segments. • t :

17

■ I ; Salivary glands (Figure 11). E ls on (1937), in hi-s com p arative

study of Kemiptera,. states, that / ,• \

' ■ The salivary glands of phytosuccivorous forms may be differentiated, ip a gene pal ways from those ©father , groxaps (predaGeous, algal and fungus feeders and; blood suckers) by their complexity. The principal glands con­ sist bf numerous finger-like, lobes, variable in size and \ ' v number. The accessory glands are elongate and tubs- ; - - V:;;_ The salivary glands in this insect are composed of three finger-like

lobes, an.x oval reservoir, and a large palm-like lobe. The glands lie in

• the posterior portion of the- thoras:, one on either side of the -dorsal sur­

face of the ventriculus,, They are very variable in size and position,

lying most often just dorsal to the large, red" repugnatorial gland reser-

yoir, butsometimes extending anteriorly into the mesothorax. Two

tubhleS originate on each gland at a point between the circular rese;r- ;.

voir and the first finger-like lobe . The ante rior tubule, the s alivaryrduct

passes forward through the thorax and into the head capsule, where it

enters the salivary syringe. The other tubule, the salivary accessory •

gland,.passes caudad to the posterior margin of the gland, then turns

: ' .' ; '.'v . ■ : ■ ! : ; >, . ■ cephalad to undergo a Series of loops in the mesothorax. From here

it passes caudad to the posterior of the gland, then runs forward all

the way into the ’head, undergoing a di'stinjct increase in diameter as it ; ,

does so, Looping back from the. head it .finally terminates blindly just

behind the main gland. 1 . THE; CIECUEM'OEY SYSTEM

■ The d o r sa l v e s s e l "with its supp orting m u sc le s is a lso m uch sim p li fied in this insect (Figure 12)» Snodgrass (1935) defines the aorta as,

o <, the slender part of the dorsal vessel continued forward from the first chamber of the heart into the headt " Snodgrass states that the cardiac region may extend as far as the first abdominal segment or even into the thorax; In Acanthocephaia, and at least one other coreid, the box elder bug, a i®verb e trend has thhen place« ■ ■ ' ■ .■ '■

Four pairs of alary .muscles suspend the dorsal vessel from the tergites of the fifth, sixth,: and eighth abdominal segments; one pair arise on the bases of the first valyifers which are extensions of segment Seven.

There appear to be two pairs of Ostia, one becurriiig subterminally in the eighth Segmehts the Other in the seventh segment. These ostia set off the heart or cardiac region of the long dorsal vessel, the true heart then lying in segments Seven and.eight. One pair of alary muscles originate:' on the lateral margins pf the fifth abdominal tergite and are inserted on the ventral heart Wali' in segment siXi.' The s econd pair originated on the lateral margins of the sixth tergite and are inserted on the ventral heart wall in the same Segment, Jknother pair priseg on the bases of the first vateifers and are inserted on the ventral heart wall in segment eight.

: The fourth pair arise on the lateral margins of the. eighth tergite and

Snodgrass |1935) states that "The diaphragm membranes'in some

brain on the dorsal surface of the pharynx. This portion of- the pharynx ; DISC OSSIQM AMD ;CONCFUSIONS

•'V :«. A lew hemipterous families have been studied quite extensively

•in regard to the internal anatomy of their members, ' Other families, >,

among them the family Coreidae, have received relatively little,such • .

attention. This study proposes to throw further light on the internal

anatomy of one of the groups that has received less• attention in the past,

and thus to- hohtribtite W.-dur. khdwtedge ■ th e ' an^toti^y; -of ~the. H em ip ter

as a whole., The female reprdductive system is of the typical he'naip-

terous type,' v/hile the male reproductive system exhibits some unusual

modifications. Thes e .modifications have occurred in groups.: other than

: the 'Cbreidae as' illustrated by the Wofktof Bonhag and Wick (1953):on = ■■ /'t

Oncopeltus faSciatus (Dygaeldae). . A highly .specialized fluid pump con- ' \

•trols the erection and extrusion of the phallus from the genital capsuie.

In Acanthocephala this pTimp ’inechanism' is present, though the ordinarily

retractible aedeagns haS become fixed fq the iririer wall of the phallobase,

the endophallus still being capable of extrusion from the aedeagus. The ,

digestive System is characteristic; of the known plant-sue king hemipter-

axis. There is"a sac-like ventriculus, followed by a tubular second shd: ,

third portions. The third region, however, is often bulbous in other plant-sucking hemipterans,,; The fourth portion is also tubular, and bears

gastric caeca for bousing bacterial According to Bison (1937) these

caeca are present on the fourth portion of the mid-intestine of plant-

sucking hemipterans but not in Such groups as the sem i- and fully pre-

daceous hem ipteranS.Pep toco rls triyittatus is generally a plant feeder but may. feed on fluids occasionally; this insect lacks gastrrcccaeca

Extreme, cephalizatioii and fusion have, taken place within the central neryous system., Similar modifications have taken place once again in •.

groups other than the coreids. • OncopeltUs fasciatus illustrates essen­ tially the same changes in the central nervous system. The three lobes of the brain and the suboesophageal ganglia have merged completely*

Cephaiization, has resulted in a nerve cord containing but two large

ganglia in the thorax. The circulatory System' shoves a reduction in the number of alary muscles and heart chambers, Es sig. (194?) .States that the Hemiptera in general have five-chambered hearts, although the heart in this insect has but one elongated chamber lying in the seventh and eighth abdominal Segments. In light of this reduction in number of heart chambers, the aorta can be considered as extending posteriorly from the hepd into the seventh abdominal segment where it merges with the heart.

Other coreids also show a reduction in the number of alary muscle's;

EeptocprlS triyittatus possesses three pairs, while Acanthocephala has ... four pairs supporting the posterior region of the dorsal vessel. A typical dorsal diaphragm is absent. . r SUMMARY \

. The morphology of the reproductive*, nervous2 digestive* and

circulatory systems of the bug* Acanthocephala* was studied in gross

detail* The reproductive system of the female is of the typical hemip­

terous '.type,' with the exception that third walvulae are absent from the

ovipositor* An articulatory apparatus and erection mechanism for the

phallus * as described by Bdnha'g and Wick (1953)* are present also in

the genitalia of this male* Fusion and cephalization of portions of the

central nervous system have occurred* These are ^ showne .. particu­

larly by the lack of any external evidence of a tritocerebrum and a total

’ of only two thoracic ganglia in the entire ventral nerve cord* The diges

five system is typical:for- the Hemiptera* Gastric caeca are borne on

the fourth region of the mid-intestine* which is very characteristic of

the plant-sucking members of this order* Although Essig (1 942) states

that the Hemiptera in’ general have five-chambered hearts* only one

heart chamber is present in the dorsal vessel of Acanthocephala* Four

pairs of alary muscles support the dorsal vessel between the fifth. and

ninth abdominal segments*

22 LITERATURE CITED

As block, Peter D. 1957. An investigation of the taxonomic value of the.phallus in the Eygaeidae (Hemiptera"Heteroptera)» Ann, Ent. Soc. A m ef0 K 5,0(4) :40 7-42 6.

Breakey, E„ P„ 1936. Histold'gieal studies of the digestive system of the squash bug. Anas a tristis DeG. (Hemiptera, Coreidae), Ann. " Ent.. Boct 'Amer.y V' ' . ' / /

Bonhag, Phillip F„ and James R« Wick» 1953. The functional anatomy of the male and female reproductive systems of the milkweed bug. Oneopeltus fasciatus (Dallas) (Heteroptera, Lygaeidae). ' ; : Jour. Morph., 93: 177-284. . ■ / y : - v

Crampton, G. C. 1922. The genitalia, of the males of certain Hemip­ tera (Heteroptera) and Hornoptera. Bull. Brooklyn Ent. Soc. ' N. Y., 17: 46-55.

Els on, J. A. 193 7. A comparative study of Hemipte ra. Ann. Ent. Soc. -Amery , XXX: 579-:597. - .

Essig, E... O. • 1942. College entomology. The Macmillan Go. , New . . York. . 900 pp. .

■ Glasgow, Hugh. 1914. The gastric caeca and caecal bacteria of the Heteroptera. Biol. Bull. , 26: 101-1.70.

Hamilton, Marion A. 1931'= The morphology of the water scorpion, Nepa cinerea E. (Rhynchota, Heteroptera). Proc. Zool. Soc. , London, 11: 1067-1136, 6 pis. , 22 text figs.

Malouf, N. S. R= 1933., Studies on the internal anatomy of the "stink bug. " Bull. Roy. Ent. Soc.. d^Egypte, 19>39 %-]£%■ .?» t e x t

: . . : '. £lS- . . . ■,' .: : . . , - a . ' Michener, C. D. 1944. A comparative study of the appendages of the eighth and ninth abdominal segments of insects. Ann. Ent. Soc. Abier., 37: 336-351. , : ' . J'. ' 23 : .. b "■ ■ ■ Newell, Azin Grace, 1918. The comparative morphology of the genitalia of insects. Ann. Ent. See. Amer. , XI (2): 109-156.

Rutschky, Charles W. and Edward Stryjak. 1955. A gross study of the nervous system of the large milkweed bug, Qncopeltus faSciatus (Dallas). Ann. Ent. Sbc. Amer. , 48(4):219-221. Illus.

Singh'-Pruthiv , 1925. The morphology of the male genitalia in BhyAchoSao , Trans. Ent. Soc. Lond., 192^s 127*=267s

Snodgrass, R-. E. 1933. Morpholdgy of the insect abdomen. Part II. The genital ducts and ovipositor. Smithsonian Miscellaneous Collections, 89(8): 1-148. • /

Snodgrass, R. E. 1935. Principles of insect morphology. McGraw- H ill Go., New Tbrk and London. 667 pp. \ '

Snodgrass, R. E, 1936= Morphology of the insect abdomen. Part III. The male genitalia (Including artbropods other than insects). Smithsonian Miscellaneous Cblle'ctiohs, 95(14):l-96.

Snodgrass, R. E. 1957. A revised interpretation of the external repro- ductiye or gans of male insects . Smithsonian Misceilaneous Col­ lections, 135(6):1-6G. \ . . ; ' ' 1 ' ; ; : ' ' . . , Weber, H. 1930. Biologip der Hemipteren. Julius Springer, Berlin.

Weber, H. 1933. Lehrbuch der Entomologie. Gustav Fischer, Jena.

Wooley, Tyler A. 1949. Studies on the internal anatomy of the box . elder bug, Leptocoris trivittatus (Say). Ann. Ent. Soc., Amer. , ' ' 42(2):203-.226, 8 pis., 31 figs. ' i

Wooley, Tyler A. 1951. The circulatory System of the box elder bug, Leptocoris trivittatus (Say). Amer. Midland Nat. , 46(3) :634- "639. 1„ Dorsal view of male reproductive system, (x 8)

2,, Anterior view of phallus, (x 25)

3. Anterior view of aedeagus and endophallus, ;(x 20)

4, Left side of brain and suboesophageal ganglion, (x 21) 25

E

H

EZ

Y

Aed t&sss VI

Stp VI ^ il' l v j ■ T Ac GL

OPdcl Gen Cop

4 5o Dorsal view of female reproductive 'system.* (x 8)

6, Yentral view? posterior region of female abdomen with first

valvifer removeda (x 11) , *;

?• ; Dor.sal view of first. valvulao (x 28)

8* Dorsal view of second valvifer and valvula» (x 36) 6 9. Dorsal view of brain and ventral nerve cord, (x 8) 9 10. Dorsal view of alimentary canal, (x 9)

11. Yentral view of left saliyary gland and accessory structures, (x X5) 28 Ventral view of dorsal blood vessel and alary m usclesG (x 11) (Jniv. of Arizona Library